U.S. patent number 6,093,199 [Application Number 09/129,682] was granted by the patent office on 2000-07-25 for intra-luminal device for treatment of body cavities and lumens and method of use.
This patent grant is currently assigned to Endovascular Technologies, Inc.. Invention is credited to Mary Bellack, Peter S. Brown, Mona Patel.
United States Patent |
6,093,199 |
Brown , et al. |
July 25, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Intra-luminal device for treatment of body cavities and lumens and
method of use
Abstract
An intra-luminal device comprises a flow retainer and/or
modulator for maintaining an embolic mass within an aneurysm and,
optionally, for diverting or modulating fluid flow, and an
anchoring element for fixating the retainer within a lumen in a
patient's body. The retainer is introduced into the body lumen and
positioned with the retainer across the entrance to a body cavity
or a body lumen with an embolic mass disposed within to prevent the
embolic mass from migrating into the patient's vasculature. The
retainer may also be a diverter or modulator used to divert or
modulate the luminal fluid flow to the entrance to the body cavity
or lumen. The anchoring element, which may be attached to the
retainer, is deployed to permanently secure the retainer within the
body lumen in the desired position.
Inventors: |
Brown; Peter S. (Palo Alto,
CA), Bellack; Mary (Redwood City, CA), Patel; Mona
(San Francisco, CA) |
Assignee: |
Endovascular Technologies, Inc.
(Menlo Park, CA)
|
Family
ID: |
22441106 |
Appl.
No.: |
09/129,682 |
Filed: |
August 5, 1998 |
Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61B
17/12118 (20130101); A61B 17/12022 (20130101); A61F
2/88 (20130101); A61F 2230/0006 (20130101); A61F
2002/016 (20130101); A61F 2230/0076 (20130101); A61F
2002/018 (20130101); A61F 2/885 (20130101); A61F
2/0108 (20200501); A61F 2220/0058 (20130101); A61F
2220/005 (20130101); A61F 2230/0091 (20130101); A61F
2230/005 (20130101); A61F 2002/823 (20130101) |
Current International
Class: |
A61B
17/12 (20060101); A61F 2/06 (20060101); A61F
2/01 (20060101); A61M 029/00 () |
Field of
Search: |
;606/200,191,194,195,198
;623/1,12 ;128/898,899 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 820 726 A2 |
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Jan 1998 |
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EP |
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02-255157 |
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Oct 1990 |
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JP |
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WO 97/48357 |
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Dec 1997 |
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WO |
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Primary Examiner: Buiz; Michael
Assistant Examiner: Trinh; Vikki
Attorney, Agent or Firm: Fulwider Patton Lee & Utecht,
LLP
Claims
What is claimed is:
1. An intra-arterial device for treating an aneurysm having an
embolic mass disposed therein, comprising:
a retainer, said retainer operating to prevent the mass from
exiting out of the aneurysm;
at least one anchoring element attached to the retainer to secure
the device adjacent to the aneurysm and maintain the retainer
positioned across the entrance to the aneurysm, said anchoring
element defined by non-overlapping structure; and
a fluid flow modulator, said fluid flow modulator including a
member that provides said fluid flow modulator with a profile that
is asymmetric and discontinuous to said anchoring element, said
fluid flow modulator operating to effect fluid flow outside of the
aneurysm.
2. The device of claim 1, wherein the retainer comprises a helical
coil.
3. The device of claim 2, wherein the helical coil is comprised of
a small radius primary coil having a large radius secondary helical
configuration.
4. The device of claim 1, wherein the retainer comprises at least
one ribbon.
5. The device of claim 1, wherein the retainer comprises a
plurality of ribbons intertwined in a mesh configuration.
6. The device of claim 1, wherein the device further comprises a
core wire attached to the at least one anchoring element and
extending longitudinally through the interior of the device.
7. The device of claim 1, further comprising a second anchoring
element attached to the retainer and generally opposite from the
first anchoring element to further secure the device at the
preselected intra-luminal location and maintain the retainer
positioned across the entrance to the aneurysm.
8. The device of claim 1, wherein the at least one anchoring
element comprises a permanently expandable element.
9. The device of claim 8, wherein the expandable element is a
coil.
10. The device of claim 9, wherein the retainer is a coil having a
diameter substantially the same as the at least one anchoring
element.
11. The device of claim 9, wherein the retainer is a coil having a
larger diameter than the at least one anchoring element.
12. The device of claim 1, wherein the retainer is a coil having a
first diameter and a second expanded diameter and is permanently
expandable from the first diameter to the second diameter.
13. The device of claim 8, wherein the expandable element is a
stent.
14. The device of claim 1, wherein the device is comprised of a
shape memory alloy.
15. The device of claim 6, wherein the retainer and the at least
one anchoring element are comprised of a shape memory alloy and the
core wire is comprised of a radiopaque material.
16. The device of claim 6, wherein the retainer and the at least
one anchoring element are comprised of a radiopaque material and
the core wire is comprised of a shape memory alloy.
17. A method for treating an aneurysm connected through an entrance
to the vasculature of a body, comprising the steps of:
providing an intra-luminal device having a retainer, at least one
anchoring element defined by non-overlapping structure attached to
the retainer and a fluid flow modulator;
providing an embolic mass;
disposing the embolic mass within the aneurysm;
disposing the device intravascularly with the retainer positioned
across the entrance to the aneurysm;
securing the device within the body vasculature by deploying the
non-overlapping structure of the at least one anchoring element
against a wall of the body vasculature; and
configuring the device so that the fluid flow modulator is
positioned to affect flow outside of the aneurysm.
18. The method of claim 17, wherein the retainer comprises a
helical coil.
19. The method of claim 18, wherein the helical coil is comprised
of a small radius primary coil having a large radius secondary
helical configuration.
20. The method of claim 17, wherein the retainer comprises at least
one ribbon.
21. The method of claim 17, wherein the retainer comprises a
plurality of ribbons intertwined in a mesh configuration.
22. The method of claim 17, wherein the device further comprises a
core wire attached to the at least one anchoring element and
extending longitudinally through the interior of the device.
23. Thc method of claim 17, further comprising a second anchoring
element attached to the retainer and generally opposite from the
first anchoring element to further secure the device at the
preselected intra-luminal location and maintain the retainer
positioned across the entrance to the aneurysm.
24. The method of claim 17, wherein the at least one anchoring
element comprises a permanently expandable element.
25. The method of claim 24, wherein the expandable element is a
coil.
26. The method of claim 25, wherein the retainer is a coil having a
diameter substantially the same as the at least one anchoring
element.
27. The method of claim 25, wherein the retainer is a coil having a
larger diameter than the at least one anchoring element.
28. The method of claim 17, wherein the retainer is a coil having a
first diameter and a second expanded diameter and is permanently
expandable from the first diameter to the second diameter.
29. The method of claim 24, wherein the expandable element is a
stent.
30. The method of claim 17, wherein the device is comprised of a
shape memory alloy.
31. The method of claim 22, wherein the retainer and the at least
one anchoring element are comprised of a shape memory alloy and the
core wire is comprised of a radiopaque material.
32. The method of claim 22, wherein the retainer and the at least
one anchoring element are comprised of a radiopaque material and
the core wire is comprised of a shape memory alloy.
33. The method of claim 17, wherein the embolic mass comprises an
embolic coil.
34. The method of claim 17, wherein the embolic mass comprises an
embolizing liquid.
35. The method of claim 17, wherein the step of disposing the
embolic mass within the aneurysm occurs prior to the step of
disposing the device intravascularly.
36. The method of claim 17, wherein the step of disposing the
embolic mass within the aneurysm occurs subsequent to the step of
securing the device within the body vasculature.
37. The device of claim 3, wherein the device further comprises a
core wire attached to the at least one anchoring element and
extending longitudinally through the interior of the device.
38. The device of claim 37, wherein the core wire is formed from a
shape memory material and the device is formed from a radiopaque
material.
39. The device of claim 37, wherein the core wire is formed from a
radiopaque material and the device is formed from a shape memory
material.
40. The method of claim 19, wherein the device further comprises a
core wire attached to the at least one anchoring element and
extending longitudinally through the interior of the device.
41. The method of claim 40, wherein the core wire is formed from a
shape memory material and the device is formed from a radiopaque
material.
42. The method of claim 40, wherein the core wire is formed from a
radiopaque material and the device is formed from a shape memory
material.
Description
BACKGROUND OF THE INVENTION
The present invention relates to intravascular methods and devices
for treating hollow spaces within a person's body such as
aneurysms, fistulas, and other body cavities and lumens, and is
particularly well adapted for the treatment of intra-cerebral
aneurysms of the cerebrovascular vessels.
The use of intravascular devices for the treatment of aneurysms has
received an increasing amount of attention in the past few years as
both the methods and devices available for intravascular procedures
have become safer. One such method involves the insertion of a
foreign body, such as an occlusion coil, within the aneurysm to
precipitate the formation of a clot or thrombus within to partially
or completely occlude the aneurysm and thus seal off the aneurysm.
This method typically poses the risk of the coil or ensuing
thrombus migrating from the aneurysm to the parent artery and
causing a thrombo-embolic stroke. This method is also limited to
the treatment of aneurysms with small necks opening into the artery
in order to ensure that the coil will remain within the aneurysm.
In another approach, a plug is inserted into the neck of a saccular
aneurysm to block off blood flow into the aneurysm. If the plug is
not sized correctly it may fall out of the aneurysm and into the
patient's vasculature. In addition, placement of such a plug
necessitates intimate contact with the aneurysm, which can cause
rupture of the aneurysm and hemorrhaging. Finally, attempts have
been made to treat both saccular and fusiform aneurysms by
deploying grafts within the vasculature and anchoring them on
either side of the aneurysm. These grafts typically extend along
the entire length of a fusiform aneurysm, or lie across the mouth
of a saccular aneurysm, thereby completely blocking off the flow of
blood to the aneurysm and relieving the pressure thereon.
One such graft is described in U.S. Pat. No. 5,693,087 for a Method
for Repairing an Abdominal Aortic Aneurysm, and consists of a tube
adapted to be disposed within an abdominal aortic aneurysm and
having a wire woven into one end of the graft that can be expanded
to sealingly engage the vessel wall. The tube is preferably made of
DACRON.RTM. and other polyester materials, TEFLON.RTM., TEFLON.RTM.
coated DACRON.RTM. and porous polyurethane. U.S. Pat. No. 5,527,355
for Apparatus and Method for Performing Aneurysm Repair discloses
an aneurysm graft with an array of staples at either end having
outward protruding barbs that lodge into the vessel wall. In
addition, an exterior band is placed around the vessel at the
positions where the barbs protrude into the vessel wall. The bands
may have a VELCRO.RTM. strap or a clasp, or may be heat sealed. In
yet another approach to the problem, U.S. Pat. No. 5,405,379
discloses a Self Expanding Vascular Endoprosthesis comprising a
sheet of resiliently flexible biocompatible material such as
polypropylene. The sheet is rolled upon itself about one of its
longitudinal edges and is introduced adjacent to the aneurysm
through a catheter to be expelled and expand to form a bridge
isolating the aneurysm from the flow of blood.
Although potentially successful in such applications as abdominal
aortic aneurysms, such devices do present a few drawbacks,
especially in applications such as intracranial aneurysms. Among
the more notable of the difficulties presented is the need to fit
such devices through a very small delivery lumen along a typically
very tortuous pathway. In addition, the longer the graft the larger
the surface area for clot formation and endothelial cell growth,
which in extreme situations can cause new complications for the
patient. Also, these devices do not have the ability to be
deployed, detached and/or retrieved as would be necessary for such
a device in the intra-cranial vessels. The risks posed by these
devices increase in magnitude when the end organ is the brain, with
its smaller vessel diameters, weaker vessel walls, and increasingly
tortuous paths. The devices described above are thus less than
ideally suited to intracranial intravascular intervention.
Moreover, any device placed in the parent artery of an intracranial
aneurysm runs the risk of occluding perforating side branches.
These perforators are small, usually less than 200 microns in
diameter, and can be the sole source of blood flow to important
tissues of the brain. Presently known devices such as vascular
grafts and stents can easily partially or completely block the flow
of blood to one or more such perforators, thereby causing
clinically significant ischemic strokes.
In light of the above, it becomes apparent that there continues to
be a need for a method to treat an aneurysm to minimize the risk of
rupture by relieving or minimizing the stress placed upon it by the
arterial blood flow with a device that can be delivered easily to
an intracranial site, deployed accurately, and used by itself or in
conjunction with other methods and devices to augment their
efficacy.
SUMMARY OF THE INVENTION
The present invention addresses the above mentioned needs by
providing a method and device for treating a body cavity or lumen,
such as a saccular aneurysm, by securing coils and other embolic
devices deployed within the aneurysm or the aneurysm neck with
devices that comprise a retainer element for placement across the
entrance to the aneurysm and one or more anchoring elements for
securing the device at the selected intravascular site. Such
devices can be inserted through small diameter, tortuous
vasculature with relative ease, deployed with accuracy, and secured
at the target site with minimal adverse impact upon the surrounding
tissue. A device according to the present invention also poses much
reduced risk of blocking off flow to perforators and other small
blood vessels, and thus is much safer to the patient when compared
with other intra-luminal devices that are placed in the parent
artery. In addition, the device is particularly well suited for
treating saccular aneurysms originating near a vessel branch.
In the preferred method of use, the device of the present invention
is used in conjunction with other aneurysm treatment methods to
enhance the efficacy and safety of these methods. Thus, an embolic
mass such as an occlusion coil is introduced into an aneurysm to
induce clot formation, following or prior to which the device of
the present invention is deployed with the retainer element across
the aneurysm neck to ensure that neither the occluding element nor
any clots migrate out of the aneurysm and out into the vasculature.
This approach is particularly beneficial in wide necked aneurysms
where embolic agents have until now been difficult or impossible to
keep in. Alternatively, an embolic agent may be introduced into the
aneurysm to substantially fill the aneurysmal cavity, following or
prior to which the device of the present invention may be deployed
with the retainer element across the entrance of the aneurysm to
ensure that the embolic agent does not migrate into the vasculature
of the patient. In another alternative method, the retainer element
may incorporate medicine that is slowly released into the aneurysm
following deployment of the device to enhance or prevent clot
formation, cell growth, scar tissue formation, and other desirable
or undesirable effects.
A further and important aspect of the device of the present
invention is its ability to be detachably connected to the delivery
device, which may be a guide wire, optic fiber, or catheter, so as
to permit the operating surgeon to accurately deploy and, if
necessary, redeploy the device with a high degree of accuracy. Once
properly deployed both in terms of position and orientation with
respect to the target cavity or lumen, the device may be detached
from the delivery device and permanently deployed within the
patient's vasculature.
The anchoring elements are preferably of the expandable type, such
as coils or stents, so as to permit the device of the present
invention to be inserted into the vasculature and to follow a
relatively tortuous pathway to the desired intravascular location.
In this manner the device of the present invention may be formed
from a self-expanding shape memory alloy, or alternatively may be
deployed using balloon catheters of the type known and used in the
art. Thus, in one preferred embodiment, the device is comprised of
self-expanding retainer and anchoring elements that can assume a
linear or stretched configuration for insertion and delivery
through a catheter or over a guide wire, and when the device is
deployed in the artery, it has a memory that returns the elements
to their coiled, expanded configuration and thus anchor itself to
the patient's vasculature at the target intravascular site.
In another aspect, the device of the present invention can be used
to treat a substantially hollow space or volume in a patient's body
having fluid flowing within (such as, for example, a body cavity
such as an aneurysm, or a body lumen such as a fistula or a vein)
by reducing at least partially the peak fluid flow and peak fluid
pressure experienced by the cavity or lumen. Therefore, in an
alternative aspect the present invention provides a device
comprising a diverter for diverting at least partially the arterial
blood flow away from the entrance of a body cavity or lumen, and
one or more anchoring elements attached to the diverter for
securing the diverter at a particular intravascular location and,
for certain embodiments, in a particular angular orientation with
respect to the entrance of the cavity or lumen. For example, the
diverter may operate to divert all or a portion of the arterial
blood flow away from the neck of an aneurysm, or to completely
block all such blood flow into the aneurysm, to the net effect of
reducing the peak blood pressure experienced by the aneurysm. The
diverter may be comprised of one or more coils, ribbons in parallel
or intertwined configurations, flexible membranes, foam pads, and
other elements formed with protrusions or surfaces for biasing the
arterial blood flow in a particular direction.
In yet another aspect of the present invention, a device is
provided including a modulator for altering the blood flow at a
preselected intravascular location relative to the entrance of a
body cavity or lumen so as to reduce the peak blood pressure
experienced within. Such a device may be used to treat saccular or
fusiform aneurysms. Depending upon the design of the modulator, the
device may be deployed upstream or downstream of the entrance of
the aneurysm. The device further includes one or more anchoring
elements for securing the modulator at the intravascular location.
The modulator may be comprised of any of the elements mentioned
previously, as well as uni- or bi-directional valves.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B depict a frontal view and an end view of an
intra-arterial device for the treatment of aneurysms according to
the present invention;
FIGS. 2A and 2B depict a frontal view and an end view of another
embodiment of the intra-arterial device of the invention;
FIGS. 3A and 3B depict a frontal view and an end view of another
embodiment of the intra-arterial device of the invention;
FIGS. 4A and 4B depict a frontal view and an end view of another
embodiment of the intra-arterial device of the invention;
FIGS. 5A and 5B depict a frontal view and an end view of another
embodiment of the intra-arterial device of the invention;
FIGS. 6A and 6B depict a frontal view and an end view of another
embodiment of the intra-arterial device of the invention; and
FIG. 7 is a frontal view, in partial cross-section, of the
intra-arterial device of FIG. 1, deployed within the vasculature of
a patient adjacent to the entrance of a saccular aneurysm having an
embolic coil disposed within; and
FIG. 8 is a frontal view, in partial cross-section, of the
intra-arterial device of FIG. 4, deployed within the vasculature of
a patient adjacent to the entrance of a saccular aneurysm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the preferred embodiment, the present invention addresses the
need for a method to treat a cavity or lumen connected to a
patient's vasculature, by acting to retain and secure one or more
embolic masses or elements disposed in the cavity or lumen for the
purpose of occluding the cavity or
lumen to the fluid flowing into it. With reference to FIGS. 1A and
1B, wherein a device for treating a saccular aneurysm is depicted,
the present invention provides device 10, comprised of a retainer
element in the form of a helical coil 60 and at least one anchoring
element 30 attached to the retainer. The embodiment depicted in
FIG. 1 comprises two anchoring elements 30, attached one each on
either side of the retainer 60. The retainer coil may be of the
same or larger radius than the anchoring elements, because the
vessel region immediately adjacent to the entrance of an aneurysm
will typically be enlarged in diameter, and the use of an enlarged
coil retainer will also serve to further anchor the device in the
proper position because the retainer coil will be able to better
lodge itself against the vascular walls at this location.
In the preferred construction of device 10, the retainer and the
anchoring elements are formed from a tightly coiled, small radius
primary coil [not shown] that is wound into a secondary helical
coil configuration having a larger radius approximately equal to
the radius of the patient's vasculature at the target site. Such a
construction offers improved flexibility and thus allows the device
to better navigate tortuous pathways such as found in the
intracranial vasculature, as well as increased resistance to
compressive forces and thus enhanced `pushability` and ability to
be delivered through small diameter micro-catheters. In addition, a
small radius primary coil construction provides increased strength
when deployed into a secondary coil configuration as compared to a
helical coil of the same diameter that is constructed from a
straight wire, and can thus better anchor itself within the
patient's vessel and resist the compressive forces exerted by the
vessel wall. Furthermore, a primary coil also imparts to the device
the ability to be delivered over a guidewire disposed within the
interior of the primary coil.
As described elsewhere in the specification, the purpose of
retainer 60 is to retain embolic devices or materials, such as
micro coils or embolic liquids, deployed within the aneurysm and
prevent the embolic devices from migrating out of the aneurysm and
into the patient's vasculature. In addition, retainer 60 will also
serve to block or divert at least a portion of the blood flow away
from the entrance to the aneurysm, and for this reason the spacing
between individual coils 62 of the retainer coil may also be
adjusted to provide varying degrees of blood flow resistance. The
coils may also have coatings applied to them, such as a layer of
foam or rubber, that may help the coils of the retainer form a good
seal therebetween. The coil may be circular or eccentric in cross
section, depending upon the particular vascular geometry of each
aneurysm deployment site. To fully utilize this advantage of the
device of the present invention, as detailed elsewhere in the
specification, it is crucial that the surgeon be able to precisely
and accurately deliver and position the device prior to permanent
deployment.
The embodiment depicted in FIG. 1 may also be formed with a
retainer coil comprised of wire that has a cross section larger
than the wire forming the anchoring elements. The wire comprising
retainer 60 may additionally differ from that of anchoring elements
30 not only in terms of cross sectional area but also cross
sectional geometry. Thus, the retainer portion of device 10 may be
formed in a flattened configuration with a broad rectangular cross
section forming a ribbon that assumes a ring shape when deployed at
the aneurysm site. The ribbon forming the retainer may lie at
different angular orientations relative to the wall of the artery,
depending upon the impact on the arterial blood flow that is
desired, and thus a ribbon sharply angled with respect to the
arterial wall will produce greater turbulence in the arterial blood
flow than a ribbon that is substantially parallel to the arterial
wall.
With more particular reference to FIG. 1B, retainer 60 is disposed
along the periphery of device 10 substantially in line with, or
alternatively, radially outside of, the circumference of anchoring
elements 30, so as to engage the vascular wall directly adjacent to
the entrance to the aneurysm when the anchoring elements are
deployed in the patient's vessel. As more fully described infra, in
use device 10 is deployed with retainer 60 overlying the entrance
of the target aneurysm so as to partially or fully block the flow
of blood into the aneurysm and to retain an intra-saccular coil or
other embolic device disposed within the aneurysm.
Anchoring elements 30 are comprised of helical coils and serve to
secure the retainer over the entrance of the aneurysm by engaging
the wall of the patient's blood vessel. The coils are preferably of
a self-expanding design and thus are preferably fabricated of a
material such as stainless steel or a shape memory alloy such as
nickel titanium. Alternatively, the anchoring elements may be
deployed through the application of radially outward expansive
force, such as provided by a dilatation balloon as detailed infra.
The use of an elastic, high hoop strength material such as
stainless steel assures that the anchoring elements will continue
to remain in secure contact with the vessel wall over extended
periods of time.
In an alternative embodiment [not shown] of the device depicted in
FIG. 1, device 10 may additionally be formed with a core wire
connected to the free end of either anchoring element 30 and
extending longitudinally through the interior of device 10 towards
the free end of the other anchoring element disposed on the
opposite side of retainer 60. Such a design offers the ability to
use different materials in the construction of the device, thereby
imparting various physical characteristics to the device. For
instance, the core wire may be formed from shape memory alloys such
as nickel titanium, thereby imparting superior shape memory
retention characteristics to the device and causing it to better
expand to a secondary, deployed configuration when delivered into
the body through a device such as a catheter, while the retainer
and/or anchoring elements may be formed from a radiopaque material
such as platinum that will allow the operating surgeon to better
visualize the position of the device within the patient's
vasculature and thus assure accurate delivery and deployment.
Conversely, the retainer and/or anchoring elements may be formed
from a shape memory alloy, while the core wire is formed from a
radiopaque material. Such a core wire construction may also be
employed with a small radius primary coil wound into a secondary
helical coil configuration, as detailed above, to further enhance
the flexibility of such a coiled coil device.
In another alternative embodiment, the device of the present
invention addresses the need for a method to treat a substantially
hollow space or volume in a patient's body having fluid flowing
thereinto, such as a body cavity or a body lumen connected to the
patient's vasculature, by relieving the stress placed upon it by
the fluid (e.g. blood) flowing into it or by occluding the cavity
or lumen to the fluid flow. The device is formed with a fluid flow
modulator element for deployment in a particular, preselected
intravascular location and orientation with respect to the entrance
to the body cavity or lumen. With respect to the following
alternative embodiments, like reference numbers are used for like
elements. With particular reference to the embodiment shown in
FIGS. 2A and 2B, device 10 comprises a fluid flow modulator in the
form of a flow diverter element 20 and at least one anchoring
element 30 attached to the diverter. The embodiment of the device
of the present invention depicted in FIG. 2 comprises two anchoring
elements 30, attached one each on either side of diverter 20. The
diverter is comprised of a foam pad with an open cell, or
alternatively closed cell, configuration. A closed cell diverter
may be employed to block blood flow into the aneurysm, thereby
maintaining the average pressure within the aneurysm at the level
existent when device is initially deployed, and further also
limiting the pressure pulses that the aneurysm will initially
experience before the voids in the foam clot off. Alternatively, an
open cell foam diverter will allow for a more compressible design
that will facilitate intravascular delivery. Either type of foam
will function equally well as a retainer for maintaining any
embolizing devices or materials within the aneurysm. Moreover, foam
diverters may also be doped with medicine and thus utilized as a
drug delivery device. The diverter may also include a flexible
membrane disposed across the foam pad to fully or partially cover
the foam pad to enhance the ability of the device to isolate the
aneurysm from the flow of blood. The diverter may be attached to
the anchoring elements by any of a number of methods, such as
gluing, melting, or welding. Alternatively, the two anchoring
elements may be attached to one another by a longitudinal wire 32,
such as would result if the two anchoring elements were formed from
a single, continuous length of wire, and the diverter may be formed
to wrap around the longitudinal wire. Materials suitable for
forming the foam pad include polyurethanes, collagen,
Poly-Sulphone.TM., hydrophilic plastics, silicone, and Cell
Guard.TM..
In the FIG. 3 embodiment of the invention, device 10 is similarly
comprised of diverter 40 attached between a pair of anchoring
elements 30. Diverter 40 is comprised of a plurality of ribbons 42
extending longitudinally between, and attached to, the anchoring
elements. The ribbons may overlap or be spaced apart from one
another to provide varying degrees of flow resistance to the blood
flow of the patient. In addition, a flexible membrane may be
disposed across the ribbons to partially or fully cover the
diverter element. This diverter embodiment is likewise deployed
directly across the entrance of the aneurysm. FIG. 4 depicts a
variation of the embodiment of FIG. 3, whereby the ribbons 52
forming the diverter 50 are intertwined so as to form a mesh or
filter. The diverter embodiments of FIGS. 3 and 4 can both be also
employed as retainer elements, similar to the embodiment of FIG.
1.
Referring to FIG. 5, the embodiment shown therein likewise
comprises two anchoring elements 30 with diverter 70 attached
therebetween. The diverter 70 is formed from an elastic membrane
that is deployed over the entrance of the target aneurysm to block
the flow of blood thereinto. The membrane may be attached to
longitudinal wire 32 connecting the two anchoring elements, or
alternatively may be mounted on a circumferential wire frame [not
shown] that is in turn attached to the anchoring elements.
With reference now to FIG. 6, another embodiment of the present
invention provides device 10 comprised of two anchoring elements 30
with a flow modulator element 80 disposed therebetween. The
anchoring elements are interconnected by generally longitudinal
wire 32, to which modulator 80 is attached by welding, brazing,
gluing, or any other of a number of known methods. The function of
the modulator is to alter the blood flow of the patient at a
particular, preselected intravascular location adjacent to the
entrance of the target aneurysm. This location may be upstream,
adjacent to, or downstream of the entrance of the aneurysm,
depending upon the configuration of the modulator.
Thus, for example, and with continued reference to FIG. 6,
modulator 80 may be comprised of a ring element formed with an
inner nub or protuberance 82 extending radially inward from its
inner surface. Such device 10 is placed upstream of the entrance to
the aneurysm and oriented with the nub disposed directly adjacent
to the entrance. The nub operates to divert blood flow away from
the entrance, thereby decreasing the amount of blood that enters
the aneurysm and thereby the overall peak pressure experienced by
the interior of the aneurysm. The ring element is formed as an
open-ended coil that can be advanced through a catheter in a linear
configuration and has shape memory properties that induce it to
assume a circular configuration when unrestrained. In this manner
the diverter may be advanced through a catheter to the deployment
site. Alternatively, the diverter may be formed as a closed
circular structure that is deployed by expandible devices such as
balloons. The nub may take the form of an increased diameter
portion along the coil, such as a secondary coil or a mass of
material soldered or brazed onto the coil. Thus, as described
previously, modulator 80 may take the form of a diverter element
that diverts arterial blood flow away from the entrance to the
aneurysm, or may be an element shaped to change the flow pattern
around the entrance to the aneurysm without necessarily diverting
the blood flow away from the aneurysm.
It must further be understood that the inventive concept of the
present invention also encompasses the use of flow modulators to
alter the fluid flow around the entrance to an aneurysm, fistula,
or similar, substantially hollow cavity or lumen in a patient's
body, and thus reduce the amount of fluid flowing into the entrance
to the cavity or lumen, thereby reducing the overall peak pressure
experienced by the tissue surrounding the cavity or lumen.
Therefore, the treatment method of the present invention also
encompasses the use of solely a modulator element, deployed
intra-luminaly within the patient's body to modulate or divert the
flow of blood or other fluid from the entrance to the body volume
to be treated. Thus, in an alternate embodiment of the device of
the present invention, a flow modulator 80 as depicted in FIG. 6A
may be formed with a multitude of coils and sized to fit within the
vessel adjacent to an aneurysm so as to be capable of being
securely deployed within the patient's vasculature without the use
of a separate anchor element. Thus, any type of flow modulator
element that is structurally adapted to being secured in a body
lumen may be employed according to the method of the present
invention to reduce the fluid pressure in a body space or volume.
Due to the cylindrical nature of body lumens, such modulators will
largely also be cylindrical in shape and formed with expandable
geometries to engage the lumen walls for secure long term
deployment. Thus, devices such as coils, stents, and balloons can
all potentially be used to treat aneurysms by the method of the
present invention.
With reference to FIG. 7, in a preferred method of use of device 10
(using the embodiment of FIG. 1 discussed previously as an
example), in a first step the device is formed from shape-memory
alloys as discussed supra and is detachably connected to a delivery
device such as a wire or optic fiber, examples of which are known
in the art and are described, among others, in U.S. Pat. Nos.
5,605,162 and Re. 33,911. Methods suitable for attaching device 10
to the delivery device include mechanical, heat actuated, and
electrolytical attachment methods, and are described, for example,
in U.S. Pat. No. 4,735,201, U.S. Pat. No. 5,108,407, U.S. Pat. No.
5,122,136, U.S. Pat. No. 5,354,295, and U.S. Pat. No. 5,540,680.
Thus, for example, the embodiment of FIG. 1 discussed previously,
consisting of a retainer element disposed between two anchoring
elements and having a core wire running longitudinally
therethrough, may be attached to a guide wire through a portion of
a material that is susceptible to electrolytic disintegration in
blood when exposed to an electric current. Alternatively, the
delivery device may comprise an optic fiber that is attached to the
device of the present invention by a glue that melts when exposed
to heat or light energy that is transmitted through the optic
fiber.
In the next step, a catheter as described for example in U.S. Pat.
No. 5,496,275, is inserted into the patient's vasculature and
advanced to the site of target aneurysm 100 with the distal tip
abutting the entrance to the aneurysm 102. An embolic device or
material is then introduced through the catheter and into the
interior of the aneurysm to fill the aneurysm and optionally induce
clot and/or thrombus formation. The embolic device may be an
embolic coil, wire, foam pad, neck plug, or any other structure
that will substantially fill the aneurysm with its mass and/or any
subsequently formed clots and/or thrombi. Such devices are
described, for example, in U.S. Pat. No. 5,766,160, U.S. Pat. No.
5,766,219, and U.S. Pat. No. 4,994,069. Alternatively, an embolic
material such as the compositions described in U.S. Pat. No.
5,580,568 and U.S. Pat. No. 5,667,767 may be introduced into the
aneurysm through the catheter to solidify therein and thus occlude
the aneurysm.
Device 10 can next be formed, or stretched, into a substantially
linear configuration and inserted into the catheter to be delivered
therethrough to the site of the aneurysm by the delivery device,
which is advanced through the catheter from outside of the
patient's body either manually by the surgeon or by an afterloader
device. At the site of the aneurysm the device is advanced out of
the distal tip of the catheter. Once deployed within the body, the
device proceeds to assume its secondary, curved configuration. As
previously described, the anchoring elements or alternatively the
core wire is preferably formed from a radiopaque
material, such as platinum or stainless steel, thereby allowing the
surgeon to track the progress and position of the device within the
vasculature of the patient by any known method or apparatus,
including fluoroscopy, ultrasound, or magnetic imaging. If the
device is not deployed properly either in terms of position or
radial orientation with respect to the entrance to the aneurysm, it
is retracted back into the catheter by pulling the delivery wire or
fiber, where it once again assumes its linear configuration, and
the catheter can then be repositioned or torqued into a different
orientation by the surgeon from outside of the patient.
Once the surgeon determines that catheter placement is optimal, the
device is redeployed out of the catheter, at which time the
anchoring elements deploy against vessel wall 110 of the patient's
vasculature to secure the device therein. The surgeon can now
actuate the attachment mechanism connecting the device to the wire
to detach the device from the wire and leave it permanently
implanted in the patient's vasculature. Thus, as discussed
previously, an electric current may be applied to the delivery wire
to cause electrolytical corrosion of a portion at the distal end of
the wire to which device 10 is attached, thereby releasing the
device from the wire. Alternatively, the delivery device may be an
optic fiber through which light energy is transmitted to a heat
susceptible mass of glue that holds device 10 attached to the
distal end of the optical fiber and that melts when exposed to the
light or the heat generated by the light transmitted through the
optic fiber. In the deployed position the retainer is biased snugly
against the entrance to the target aneurysm, and the coils of the
retainer act as a barrier to the embolic device or material within
while also acting as a filter across the entrance, thereby reducing
the amount of blood reaching the entrance and eventually the
interior of the aneurysm, and thus also reducing the peak blood
pressure inside the aneurysm.
Alternatively, the embolic device or material may be introduced
into the aneurysm after device 10 has been deployed, thereby
reducing the likelihood that the embolic mass will migrate from
within the aneurysm before device has been deployed to secure it
therein. In order to practice this method of use of the present
invention, the retainer of device 10 must be formed in a
configuration that allows the embolic device or material to be
delivered therethrough. For instance, the coil retainer depicted in
FIG. 1, the ribbon diverter of FIGS. 3 and 4, and the coil
modulator of FIG. 6 can all be employed in this manner of use of
the device of the present invention.
With reference now to FIG. 8 [depicting use of the embodiment of
FIG. 4], in another preferred method of use of the device of the
present invention, the device is first mounted upon the balloon of
a conventional balloon catheter of the type known in the art for
delivering stents and the like, such as are described, for example,
in U.S. Pat. No. 5,449,343 and U.S. Pat. No. 5,709,658, so that
both anchoring elements overlie the balloon along the entire length
of each anchoring element. The placement of the diverter along the
periphery of the device facilitates this mounting procedure because
it leaves the interior of the device relatively unobscured for the
balloon to be inserted therein. Once the device has been securely
mounted to the balloon of the delivery catheter, the physician may
proceed to insert the catheter into the vasculature of the patient
and advance the balloon with the device towards the site of the
target aneurysm until the device is positioned such that the
diverter is adjacent to the entrance of the aneurysm. Because the
device is securely mounted to the balloon of the delivery catheter,
the surgeon may repeatedly reposition the device by withdrawing and
reinserting the catheter until the device is optimally positioned
adjacent to the aneurysm. The device of FIG. 4, for example, must
be positioned with the diverter overlying the entrance of the
aneurysm, a task that the operating surgeon may easily accomplish
by torquing the catheter so as to orient the diverter to cover the
entrance of the aneurysm. Once the device has been properly
positioned, the anchoring elements are deployed by dilating the
balloon of the delivery catheter, thereby expanding the anchoring
elements against the vessel wall of the patient and securing the
device therein.
An important consideration in the use of the device of the present
invention is the proper orientation of the retainer, diverter, or
modulator element with respect to the entrance to the aneurysm. The
ability to repeatedly insert and withdraw the device prior to
permanent deployment is one method of allowing the surgeon to
achieve the proper orientation. In addition, the device may be
designed with a self-orienting feature, so as to automatically
self-expand and deploy the diverter in the proper orientation with
respect to the aneurysm. Such a self-orientation feature may, for
example, be actuated by the flow of blood into the aneurysm, which
creates a zone of lower pressure at the mouth of the aneurysm and
which could thus help orient the diverter across the mouth of the
aneurysm. Self-orientation could also be predicated upon the
particular geometry of the deployment site, such as the enlargement
of the native vessel diameter in close proximity to the mouth of
the aneurysm, whereby the device may be sized and configured so as
to fit in a specific orientation at the site.
In addition, the device of the present invention can also be used
to promote scar tissue formation and endothelial cell growth by
incorporating medicine into the retainer or modulator element for
release over a period of time subsequent to deployment of the
device. In such an application the retainer or modulator is
preferably formed from a material exhibiting affinity for the
particular medication to be applied, and may include polymeric
material such as is described in U.S. Pat. No. 5,605,696. In this
manner, the device of the present invention may be used to
simultaneously practice two different methods for treating an
aneurysm to reduce the likelihood of rupture, namely inducing cell
growth to strengthen the aneurysm tissue and also reducing the peak
blood pressure experienced by the aneurysm tissue.
The device of the present invention can also be employed to treat
body lumens, such as arterial fistulas. A fistula is an alternate
blood flow path that develops between an artery and a vein, and
that may cause severe health problems by starving downstream tissue
of blood as well as exposing other tissue to increased blood
pressure. Typically coils have been used to embolize fistulas and
thus block the alternate blood flow path. A device according to the
present invention may instead be deployed with the retainer or
modulator element placed across the arterial entrance to the
fistula to block or divert the flow of blood away from the entrance
to the fistula to reduce the amount of blood flowing into the
fistula and thus alleviate the peak blood pressure experienced by
the fistula and any surrounding tissue.
It must be understood that the embodiments detailed previously are
for exemplary purposes only, and the present invention is not
limited solely to these examples. Rather, the inventive concept
comprised by the method and device of the present invention is the
treatment of a body cavity or a body lumen through the
intravascular placement of detachable fluid flow altering or
blocking devices within the patient's vessel in the vicinity of the
entrance of the cavity or lumen to prevent embolic devices and
materials as well as the patient's blood from moving into and out
of the cavity or lumen, thereby ensuring occlusion of the cavity or
lumen and/or reducing the blood pressure adjacent to and at the
entrance of the cavity or lumen. Thus, the present invention also
allows the treatment of an aneurysm or a fistula without
necessitating the placement of any foreign objects within the
aneurysm itself or its entrance. In addition, once positioned, the
device of the present invention is securely deployed within the
patient's vessel and poses no risk of becoming dislodged and
drifting downstream to potentially cause a stroke or other
complications.
The anchoring elements described above are likewise not intended as
limitations upon the practice of the present invention, but are
rather merely illustrative. Thus, a retainer or modulator element
may be deployed with a single anchoring element, or alternatively
three or more anchoring elements, depending upon the topography of
the particular intravascular deployment site. In addition, the
anchoring elements may consist of any one of a number of expanding,
stent or stent-like devices, and are not limited solely to helical
coils. In addition, the anchoring elements may be of the
self-expanding type, such as for example shape-memory devices
formed from NiTi and other shape memory alloys, or of high modulus
of elasticity stainless steel.
The anchoring elements are typically used to attach the device to
the delivery vehicle, although the present invention also
encompasses the concept of attaching the diverter or modulator
element of the device to the delivery vehicle. Attachment may be
mechanical, as for example mounting the anchoring elements upon the
balloon of a catheter, or attaching the diverter or modulator or at
least one of the anchoring elements to a wire (such as through a
releasable clasp or a threaded connector); or alternatively
chemical (e.g. a glue that dissolves when exposed to blood) or
electrochemical (e.g. welding the device to the wire with a
material that corrodes in blood when electrically charged). A wide
variety of possibilities exist for detachably connecting the device
of the present invention to any intravascular delivery device, all
of which are encompassed by the concept of the present
invention.
Moreover, the anchoring element or elements may be separate from
the diverter, and in use the diverter is first deployed at the
preselected intravascular location, following which the anchoring
element is deployed so as to anchor the diverter securely in place.
Thus, by way of example, modulator 80 of FIG. 6A may be deployed
through a catheter and positioned across the entrance to an
aneurysm, in the manner described previously, with nub 82 overlying
the entrance to the aneurysm. Once modulator 80 is properly
positioned, anchoring element 30 can be introduced through the same
catheter and deployed axially through the modulator, so that as the
anchoring element expands against the vessel wall the modulator is
further expanded and anchored against the vessel wall along with
it. Such a method of use of the device of the present invention may
be advantageous in certain situations where the particular
configuration of the aneurysm intravascular site renders it
difficult to deploy a modulator and anchoring element or elements
simultaneously, such as in particularly tortuous vessels where an
anchoring element attached to the modulator would make precise
positioning of the modulator unwieldy and imprecise.
In a previously disclosed embodiment, both the diverter and the
anchoring element were disclosed as comprising helical coils. It
must be understood that the present invention encompasses the
concept of structurally identical retainer and anchor elements,
such as helical coils, that only differ in their intended function.
Thus, for example, both the anchor and the retainer or modulator
elements may comprise identical helical coils, whereby the anchor
coil secures the retainer or modulator coil across the entrance to
the target aneurysm. In an alternative embodiment of such a device,
the turns of the helical coils comprising the retainer or modulator
and the anchor elements may turn in opposite directions.
It will therefore be apparent from the foregoing that while
particular forms of the invention have been illustrated and
described, various modifications can be made without departing from
the spirit and scope of the invention. Accordingly, it is not
intended that the invention be limited, except as by the appended
claims.
* * * * *